From Wikipedia, the free encyclopedia - The 2011 Fukushima Daiichi nuclear disaster, the worst nuclear incident in 25 years, displaced 50,000 households after radioactive material leaked into the air, soil and sea.[1] Radiation checks led to bans on some shipments of vegetables and fish.[2]

Map of contaminated areas around the plant (22 March – 3 April).Fukushima dose rate comparison to other incidents and standards, with graph of recorded radiation levels and specific accident events from 11 to 30 March.

Radiation hotspot in Kashiwa, February 2012.The radiation effects from the Fukushima Daiichi nuclear disaster are the observed and predicted effects resulting from the release of radioactive isotopes from the Fukushima Daiichi Nuclear Power Plant after the 2011 Tōhoku earthquake and tsunami. Radioactive isotopes were released from reactor containment vessels as a result of venting to reduce gaseous pressure, and the discharge of coolant water into the sea[citation needed]. This resulted in Japanese authorities implementing a 20 km exclusion zone around the power plant, and the continued displacement of approximately 156,000 people as of early 2013.[3] Trace quantities of radioactive particles from the incident, including iodine-131 and caesium-134/137, have since been detected around the world.[4][5][6] As of early 2013, no physical health effects due to radiation had been observed among the public or Fukushima Daiichi Nuclear Power Plant workers. That being said, TEPCO and GE do not have a policy that requires them to monitor these supposed effects.[7][8]People in the area worst affected have a slightly higher risk of developing certain cancers.[9] The World Health Organization (WHO) released a report that estimates an increase in risk for specific cancers for certain subsets of the population inside the Fukushima Prefecture. For the populations living in the most contaminated regions within Fukushima prefecture, this includes a 4% increase for solid cancers in females exposed as infants, a 6% increase in breast cancer in females exposed as infants, and a 7% increase in leukaemia for males exposed as infants. The risk of thyroid cancer in females exposed as infants has risen from a lifetime risk of 0.75% to 1.25%.[9]Preliminary dose-estimation reports by WHO and the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) indicate that, outside the geographical areas most affected by radiation, even in locations within Fukushima prefecture, the predicted risks remain low and no observable increases in cancer above natural variation in baseline rates are anticipated.[10] After the Chernobyl accident, only 0.1% of the 110,000 cleanup workers surveyed have so far developed leukemia, although not all cases resulted from the accident.[11][12] However 167 Fukushima plant workers received radiation doses that slightly elevate their risk of developing cancer.[11][13][14] Estimated effective doses from the accident outside of Japan are considered to be below (or far below) the dose levels regarded as very small by the international radiological protection community.[15] The United Nations Scientific Committee on the Effects of Atomic Radiation is expected to release a final report on the effects of radiation exposure from the accident by the end of 2013.[14]A June 2012 Stanford University study estimated, using a linear no-threshold model, that the radiation release from the Fukushima Daiichi nuclear plant could cause 130 deaths from cancer globally (the lower bound for the estimater being 15 and the upper bound 1100) and 180 cancer cases in total (the lower bound being 24 and the upper bound 1800), most of which are estimated to occur in Japan. Radiation exposure to workers at the plant was projected to result in 2 to 12 deaths.[16] However, a December 2012 UNSCEAR statement to the Fukushima Ministerial Conference on Nuclear Safety advised that "[b]ecause of the great uncertainties in risk estimates at very low doses, UNSCEAR does not recommend multiplying very low doses by large numbers of individuals to estimate numbers of radiation-induced health effects within a population exposed to incremental doses at levels equivalent to or lower than natural background levels."[7]Contents [hide] 1 Health effects1.1 Plight of evacuees2 Total emissions2.1 Air releases2.1.1 Iodine-1312.1.2 Tellurium-129m2.1.3 Caesium-1372.1.4 Strontium 902.1.5 Plutonium isotopes2.2 Water releases3 Radiation at the plant site3.1 Exposure of workers3.1.1 Iodine-intake3.2 Radiation within the primary containment of the reactors3.3 Radiation outside primary containment of the reactors3.4 Site contamination3.4.1 Soil3.4.2 Air and direct radiation3.5 Discharge to seawater and contaminated sealife4 Radiation and nuclide detection in Japan4.1 Air exposure within 30 kilometers4.2 Most detailed radiation map published by the Japanese government4.3 Ground and water contamination within 30 kilometers4.4 Air exposure outside of 30 kilometers4.4.1 Radioactive dust particles4.5 Ground, water and sewage contamination outside of 30 kilometers4.5.1 Cesium-134 & Cesium-137 soil-radiation-map4.5.2 Computer simulations of cesium contamination4.5.3 Elementary school yard in Tokyo4.6 Radiation exposure in the city of Fukushima4.7 Disposal of radioactive ash4.8 Deposition of radioactivity and effect on agricultural products and building materials4.8.1 Summary of restrictions imposed by the Japanese government as of 25 April 20114.8.2 Agricultural products4.8.3 Cattle and beef4.8.4 Natto4.8.5 Tea-leaves4.8.6 Rice4.8.7 Noodles4.8.8 Mushrooms4.8.9 Drinking water4.8.10 Breast milk4.8.11 Baby-milk4.8.12 Children4.8.13 Soil4.8.14 Wildlife4.8.15 Plankton4.8.16 Building materials4.9 Hot spots at school-yards4.9.1 New radiation limits for food in Japan5 Decontamination efforts6 Distribution outside Japan6.1 Distribution by sea6.2 Distribution by air7 Response in other countries7.1 Rush for iodine7.2 U.S. military8 Isotopes of concern8.1 Regulatory levels9 Summarised daily events10 See also11 References12 Sources13 External linksHealth effects[edit]

Preliminary dose-estimation reports by the World Health Organization and United Nations Scientific Committee on the Effects of Atomic Radiation indicate that 167 plant workers received radiation doses that slightly elevate their risk of developing cancer, however like the Chernobyl nuclear disaster that it may not be statistically detectable.[12] After the Chernobyl accident, only 0.1% of the 110,000 cleanup workers surveyed have so far developed leukemia, although not all cases resulted from the accident[11][13][14] Estimated effective doses from the accident outside of Japan are considered to be below (or far below) the dose levels regarded as very small by the international radiological protection community.[13]According to the Japanese Government, 180,592 people in the general population were screened in March 2011 for radiation exposure and no case was found which affects health.[17] Thirty workers conducting operations at the plant had exposure levels greater than 100 mSv.[18] It is believed that the health effects of the radiation release are primarily psychological rather than physical effects. Even in the most severely affected areas, radiation doses never reached more than a quarter of the radiation dose linked to an increase in cancer risk. (25 mSv whereas 100 mSv has been linked to an increase in cancer rates among victims at Hiroshima and Nagasaki) However, people who have been evacuated have suffered from depression and other mental health effects.[3]While there were no deaths caused by radiation exposure, approximately 18,500 people died due to the earthquake and tsunami. Very few cancers would be expected as a result of the very low radiation doses received by the public.[19] Stanford University professor Mark Z. Jacobson and his colleague John Ten Hoeve suggest that according to the linear no-threshold model (LNT model) the accident is most likely to cause an eventual total of 130 cancer deaths.[20][21] Radiation epidemiologist Roy Shore contends that estimating health effects in a population from the LNT model "is not wise because of the uncertainties".[22] The LNT model did not accurately model casualties from Chernobyl, Hiroshima or Nagasaki; it greatly overestimated the casualties. Evidence that the LNT model is a gross distortion of damage from radiation has existed since 1946, and was suppressed by Nobel Prize winner Hermann Muller in favour of assertions that no amount of radiation is safe.[23][24][25]In 2013 (two years after the incident), the World Health Organization indicated that the residents of the area who were evacuated were exposed to so little radiation that radiation induced health impacts are likely to be below detectable levels.[26] The health risks in the WHO assessment attributable to the Fukushima radiation release were calculated by largely applying the conservative Linear no-threshold model of radiation exposure, a model that assumes even the smallest amount of radiation exposure will cause a negative health effect.[27]The World Health Organization(WHO) report released in 2013 predicts that for populations living around the Fukushima nuclear power plant there is a 70% higher relative risk of developing thyroid cancer for females exposed as infants, and a 7% higher relative risk of leukemia in males exposed as infants and a 6% higher relative risk of breast cancer in females exposed as infants.[28] With the WHO communicating that the values stated in that section of their report are relative increases, and not representative of the absolute increase of developing these cancers, as the lifetime absolute baseline chance of developing thyroid cancer in females is 0.75%, with the Radiation-induced cancer chance now predicted to increase that 0.75% to 1.25%, with this 0.75% to 1.25% change being responsible for the "70% higher relative risk":[28]These percentages represent estimated relative increases over the baseline rates and are not absolute risks for developing such cancers. Due to the low baseline rates of thyroid cancer, even a large relative increase represents a small absolute increase in risks. For example, the baseline lifetime risk of thyroid cancer for females is just (0.75%)three-quarters of one percent and the additional lifetime risk estimated in this assessment for a female infant exposed in the most affected location is (0.5%)one-half of one percent.The WHO calculations determined that the most at risk group, infants, who were in the most affected area, would experience an absolute increase in the risk of cancer (of all types) during their lifetime, of approximately 1% due to the accident. With the lifetime risk increase for thyroid cancer, due to the accident, for a female infant, in the most affected radiation location, being estimated to be one half of one percent[0.5%].[28][29] Cancer risks for the unborn child are considered to be similar to those in 1 year old infants.[30]The estimated risk of cancer to people who were children and adults during the Fukushima accident, in the most affected area, was determined to be lower again when compared to the most at risk group - infants.[31] A thyroid ultrasound screening programme is currently[2013] ongoing in the entire Fukushima prefecture, this screening programme is, due to the screening effect, likely to lead to an increase in the incidence of thyroid disease due to early detection of non-symptomatic disease cases.[32] About one-third of people[~30%] in industrialized nations are presently diagnosed with cancer during their lifetimes, radiation exposure can increase cancer risk, with the cancers that arise being indistinguishable from cancers resulting from other causes.[33]In the general population, no increase is expected in the in the frequency of tissue reactions attributable to radiation exposure and no increase is expected in the incidence of congenital or developmental abnormalities, including cognitive impairment attributable to in utero radiation exposure.[34] No significant increase in heritable effects has been found in studies of the children of the survivors of the atomic bombings of Hiroshima and Nagasaki or in the offspring of cancer survivors treated with radiotherapy, which indicates that moderate acute radiation exposures have little impact on the overall risk of heritable effects in humans.[35]As of August 2013, there have been more than 40 children newly diagnosed with thyroid cancer and other cancers in Fukushima prefecture 18 of which were diagnosed with thyroid cancer, but these cancers are not attributed to radiation from Fukushima, as similar patterns occurred before the accident in 2006 in Japan, with 1 in 100,000 children per year developing thyroid cancer in that year, that is, this is not higher than the pre-accident rate. While controversial scientist Christopher Busby disagrees, claiming the rate of thyroid cancer in Japan was 0.0 children per 100,000 in 2005, the Japan Cancer Surveillance Research Group showed a thyroid cancer rate of 1.3 per 100,000 children in 2005 based on official cancer cases.[25] As a point of comparison, thyroid cancer incidence rates after the Chernobyl accident of 1986 did not begin to increase above the prior baseline value of about 0.7 cases per 100,000 people per year, until 1989 to 1991, 3 to 5 years after the accident in both the adolescent and children age groups, therefore data from Chernobyl suggests that an increase in thyroid cancer around Fukushima is not expected to begin to be seen until at least 3 to 5 years after the accident[36][37]A 2013 article in the Stars and Stripes asserted that a Japanese government study[which?] released in February of that year had found that more than 25 times as many people in the area had developed thyroid cancer compared with data from before the disaster.[38][unreliable source?]As part of the ongoing precautionary ultrasound screening program in and around Fukushima, (36%) of children in Fukushima Prefecture in 2012 were found to have abnormal growths in their thyroid glands, but these are not attributed to the effects of radiation.[39] This screening programme is, due to the screening effect, likely, according to the WHO, to lead to an increase in the incidence of the diagnosis of thyroid disease due to early detection of non-symptomatic disease cases.[32] For example, the overwhelming majority of thyroid growths prior to the accident, and in other parts of the world, are overdiagnosed (that is, a benign growth that will never cause any symptoms, illness, or death for the patient, even if nothing is ever done about the growth) with autopsy studies, again done prior to the accident and in other parts of the world, on people who died from other causes showing that more than one third (33%+), of adults technically has a thyroid growth/cancer, but it is benign/never caused them any harm.[40]Thyroid cancer is one of the most survivable cancers, with an approximate 94% survival rate after first diagnosis, and that rate increases to a 100% survival rate with catching it early.[41] For example, from 1989 to 2005, an excess of 4000 children and adolescent cases of thyroid cancer were observed in those who lived around Chernobyl, of these 4000 people, nine have died so far, a 99% survival rate.[42]Plight of evacuees[edit]A survey by the newspaper Mainichi Shimbun computed that there were 1,600 deaths related the evacuation comparable to the 1,599 deaths due to the earthquake and tsunami in the Fukushima Prefecture.[43]